Reply by a1Jim

The reason stickering is important is equal air flow around the wood ,as an example if you take a piece of bread and put it flat on your counter top the top of the bread will be much dryer than the side that’s face down. When the same thing is done to wood the top drys faster than the area faced down on the bench. This causes warping. As far as your concrete floor ,Concrete holds a lot of moisture and if wood is stacked on a concrete floor or even a foot above it the wood on the bottom is taking on moisture where the wood on the top is drying out faster especially in a heated space.You guessed it more warping. Then there are the other causes of bowing and twisting ,including intertention,and the wood not being dry enough to be stable.